Rename media::Clock to media::TimeDeltaInterpolator and update API.

media/base/time_delta_interpolator.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/base/time_delta_interpolator.h"
+
+#include <algorithm>
+
+#include "base/logging.h"
+#include "base/time/tick_clock.h"
+#include "media/base/buffers.h"
+
+namespace media {
+
+TimeDeltaInterpolator::TimeDeltaInterpolator(base::TickClock* tick_clock)
+    : tick_clock_(tick_clock),
+      interpolating_(false),
+      upper_bound_(kNoTimestamp()),
+      playback_rate_(1.0f) {
+  DCHECK(tick_clock_);
+}
+
+TimeDeltaInterpolator::~TimeDeltaInterpolator() {
+}
+
+base::TimeDelta TimeDeltaInterpolator::StartInterpolating() {
+  DCHECK(!interpolating_);
+  reference_ = tick_clock_->NowTicks();
+  interpolating_ = true;
+  return lower_bound_;
+}
+
+base::TimeDelta TimeDeltaInterpolator::StopInterpolating() {
+  DCHECK(interpolating_);
+  lower_bound_ = GetInterpolatedTime();
+  interpolating_ = false;
+  return lower_bound_;
+}
+
+void TimeDeltaInterpolator::SetPlaybackRate(float playback_rate) {
+  lower_bound_ = GetInterpolatedTime();
+  reference_ = tick_clock_->NowTicks();
+  playback_rate_ = playback_rate;
+}
+
+void TimeDeltaInterpolator::SetBounds(base::TimeDelta lower_bound,
+                                      base::TimeDelta upper_bound) {
+  DCHECK(lower_bound <= upper_bound);
+  DCHECK(lower_bound != kNoTimestamp());
+
+  lower_bound_ = std::max(base::TimeDelta(), lower_bound);
+  upper_bound_ = std::max(base::TimeDelta(), upper_bound);
+  reference_ = tick_clock_->NowTicks();
+}
+
+void TimeDeltaInterpolator::SetUpperBound(base::TimeDelta upper_bound) {
+  DCHECK(upper_bound != kNoTimestamp());
+
+  lower_bound_ = GetInterpolatedTime();
+  reference_ = tick_clock_->NowTicks();
+  upper_bound_ = upper_bound;
+}
+
+base::TimeDelta TimeDeltaInterpolator::GetInterpolatedTime() {
+  if (!interpolating_)
+    return lower_bound_;
+
+  int64 now_us = (tick_clock_->NowTicks() - reference_).InMicroseconds();
+  now_us = static_cast<int64>(now_us * playback_rate_);
+  base::TimeDelta interpolated_time =
+      lower_bound_ + base::TimeDelta::FromMicroseconds(now_us);
+
+  if (upper_bound_ == kNoTimestamp())
+    return interpolated_time;
+
+  return std::min(interpolated_time, upper_bound_);
+}
+
+}  // namespace media